Motor-control system.



JIEATON.

NlOTQRCONTROL SYSTEM. APPLICATION FILED APR.23, 1915. RENEWED JAN.3,1919.

1,299,924. Patented Apr. 8,1919.

Iri-Q 7'0 POSITION SHOW Y Inventor": Jo hn Eaton,

His Jitter-Beg.

UNITED STATES i rnrnnr onmon.

JoHn Enron, or scnnnncranv, NEW YORK, AssIGNon no GENERAL nnnc'rnrccomm, a conronn'rron' on NEW max. I

moroa-con'rnon-srsrnm.

Specification of Letters Patent.

Patented Apr. 8, 1919.

Application filed April 23, 1915, Serial No.23,339. Renewed January3,1919. Serial No. 269,417.

To all whom it may concern: 7

Be it known that I, JOHN Enron, a sub ject of the King of Great Britain,residing at Schenectady, county of Schenectady, State of New York, haveinvented certain the like and has for its object the provision of meanswhereby the control of such operation is effected in a reliable andeificient manner. r

My invention relates more specifically to combined hand and automaticcontrol for electric motors for driving planers and the like. In theoperation of electrically driven planers, it is frequently desirable tobe able to control the planer from positions remote from the mastercontroller or reversing switch, which is actuated by. dogs on the platenof the machine.

Heretofore it has been necessary forithe operator to manipulate thereversing switch in order to get the required small movements or inchingnecessary in adjustin' the work. To make it possible to operate t ereversing switch from both sides of the ma chine, it is necessary thatanoperating shaft for the. reversing switch extend across the machine andthe operator is then limited to these two positions on opposite sides ofthe machine for manipulation. In large planers this is extremelyawkward, since the operator may be machining a'large casting which Iwill be of considerab height,"so as to make it necessary for him inorder to see the work, to climb upon the machine. Under thesecircumstances, when the operator isadjusting the work, he may have toclimb up and down a number of times before hegets the work adjusted. Inother words, he cannot see the work while he ismanipulating thereversing switch. Another difficulty with this arrangement lies in-the'fact that the operator has to very carefully consider which way tothrow the reversing switch, since if he makes a mistake, it may be veryserious. He must also look carefully to the position of the reversingswitch before he 1 the control from automatic to manual and vice versaand a switch mechanism plainly marked to indicate the out and returnmovement. This control may take the form of push buttons, one of whichwhen pressed will cause the motor to travel in the cutting? direction aslong as the button is held 1n the closed position, but upon releasing.

the button the machine will stop. Likewise, on pressing the returnbutton the reverse operation will be accomplished. The arran'gement issuch that the speed at which the motoroperatesunder the. manual conthestarting resistance in the motor circuit.

With my arrangement the operator, in any position in which it may benecessary for him to be located in orderto inspect the work, may havecomplete control 'athand. He may stop the motor at anytime under normaloperation by simply throwing switch which changes from automatlc to handoperation. 7 He may then start the motor in either direction at a slow 5eed and continue it as long as desired. Furt ermore the operator neednever be concerned about which way the machine will move when he closes'the circuit breaker, since the machine cannot be started under anycondition until one of the push buttons .is operated which will fix thedirection of operation.

- In one form of my invention, this result is brought about by employinga master conthe troller or reversing switch which is normally biasedtoreturn to a neutral or intermediate position. When the master switch isthrown to either position by the planer dogs, it only remains in thatposition for an instant and then returns to its normal position. Thisarrangement is made possi le by having maintainin' circuits for theswitches controlled by t e master controller, so that after the switchesare .once operated, they will be held in closed position by a circuitclosed at contacts in the neutral position or the troller. To myprevious application Ser. No. 817,365 filed February 7th, 1914;, T havedescribed and claimed a system in which there is a manual control forplaner operating motors in addition to the automatic control. While ingeneral this is satisiactory, it does not give the complete and safecontrol then quickly climb up again to see that every thing is workingsatisfactorily. With my present control, he never needs to leave hispoint of observation nor does he need to be concerned about which waythe machine will operate when the'circuitbreaker is closed.

Tn the agcompanying drawing, 1 have shown my invention applied to aplaner control system of the general type described in the patent toMurphy and Eaton, #1,0tl,84c5. Tn addition to the features disclosed inthe said patent, my present system also discloses additional featureswhich are described and claimed in my previous applications aboverelierred to. in order, however, that the operation of my system as awhole may be cleanl shall describe it in its entirety and then point outthe features of novelty. 4

Referring to the drawing which shows diagrammatically. one embodiment ofmy invention, A. represents the armature and F the shunt held of anelectric motor for driving a planer or the like. The direction ofrotation of this motor is controlled by four electromagnetic switches orcontactors, two for each direction of rotation. Two oi these switchesare designated as C and (3', respectively for driving in the forward orcutting direction, while the other two switches, designated as R and litrespectively, when closed drive the planer in the opposite or returndirection. These four switches are operated by shunt windings controlledby a master switch S which is biased to assume the intermediate orneutral position shown in the drawings of the apparatus hereinafterdescribed. In the drawing the parts are shown in the position theyassume when the circuit breaker is open and all parts deenergized. Whenthe line is energized by the closing of the circuit breaker CB andthemaster controller S is moved so as to engage the finger 10, the windingsof the mo em connected so as to close and short circuit the resistancewhen the counter-electromotive iorce oi the motor rises to apredetermined value. For varying the speed or the motor, I have providedtwo rheostats, one of which has a resistance T, which is controlled bythe arm 13, while the other has a resistance 1" controlled by the armis. When the motor is started, the switch 12 'is open and both of theresistances 1' and .r are short circuited through the wire 15 and theswitch 16, which isspring closed. When the switch 12 closes the switch16 is-opcned so as to break the short circuit. With the master switch Sin engagement with the finger it), that is, in the cutting position, aportion of the resistance r, the amount of which will depend upon theposition of the lever 13, will be connected in'the field circuit. Whenthe master switch is moved to the opposite position, the connection tothe arm 13 ot the rheostat is broken by the closing of the linecontactor it so that through the connection at the arm it all of theresistance r as well as a portion of the resistance r will now be in thefield circuit.

In order to bring the motor armature to rest quickly, ll provide a brakeresistance through which the motor armature is short circuited. Thisbrake resistance is divided into two sections BR and B'R. pose of thesetwo sections otresistance is to aduate the dynamic braking current asthe field builds up and the motor slows down. For making the dynamicbraking connections, ll provide the contactor B. This contactor isnormally held closed by a spring 17. The winding of this contactor isconnected across the armature of the motor so that while the motor isoperating the winding tends to close the switch. T have likewiseprovided a series winding 18 which is not energized until the contactoris closed. The five contactors R, R, G, C and B being arranged as shownin the drawings are provided with tour mechanical interlocks, 19, 20,21, and 22, cotiperating with the contactors so as to compel operationin a predetermined manner. The structure of these interlocks forms nopart of my invention, but for purposes of illustration, T have shownthem pivoted at their middle points and engaged by upwardly projectingstems of two adjacent contactors in the The pur- I out furtherdescription. While the contactor B is closed by' a spring, this springis not sufliciently'stifi', to. apply any considerable pressure to thecontacts, since electromagnetic means are'provided for holding thecontacts tightly closed.

The line contactors are provided with means for preventing their closureexcept when the field of the motor is of a predetermined strength. Thismeans consists of resistances 23 and 24 interlocked as hereinafterdescribed with the contactor which controls the brake resistance BR.Electromagnetic switch or relay 25 is provided with a winding having oneterminal connected with the shunt field F while the other end isconnected with the resistance r. The winding of this relay is dividedinto two halves which are differential or oppose each other, so thatwhen the two halves are energized they neutralize each other and therelay will not close. It is obvious that when the switch 16 is opened,the field current must pass through the two diiferential portions of therelay winding and through any field resistance-which may be in circuit,to the negative side of the line. The relay is thereforeinoperativeunder this condition. When however, the=switch 16 is closedthe upper half of the relay winding and the resistance areshort-circuited so that one half the winding is energized and the relaybecomes active. The winding of this relay is so adjusted that when thefield current approaches a maximum, that is when the field is nearlyfull strength, therelay will close, but when the field is weak, therelay will not close even though only one of the windings isenergized.When the switch 16 closes, the field resistance is short-circuited so asto strengthen the field, but the field increases gradually due to theinductive effect and until the field current rises to the predeterminedvalue, which is preferable near the maximum, the relay 25 will notoperate. When it does operate, it short circuits a section of brakeresistance BR. This relay 25 is provided with an interlocking contact 26connected with the resistance 2 k in parallel with the line contactorsso that when the -relay 25 closes, the circuit of the resistance 2 1will be open to permit the line contactors to close.

In order to obtain the same dynamic brak- 55 ing effect when the motoris reversed from high speed as when it is reversed from low speed, Iprovide means whereby a portion of the braking resistance is shortcircuited when the motor is dynamically braked from 60 one direction ofrotation so that dynamic braking takes place only through a portion ofthe braking resistance, while when the motor is reversed from theopposite direction of rotation, the braking occurs through 65 the wholebraking resistance. For accomhas two windings, one-of which, 28, is con-.closed by the-potential coil alone so that ranged thatwhen the dynamicbraking circuit is closed with the motor rotating in the cutting orforward-direction, it will be closed, but will not be closed when thedynamic braking circuit is closed with the motor rotating in theopposite or return direction. To this end the magnetic switch nectedacross the line, while the other winding, 29, is connected across themotor armature. These two windings are so proportioned that when the.counter-electromotive force of the motor opposes the voltage applied tothe winding 28 the switch will remain open, but when thecounter-electromotive force is reversed, the relay will close.Furthermore, this relay is arranged to be when the counter-electromotivewinding29 is opposing the winding 28, the switch will not close untilthe counter electromotive force reaches a low value, that is, when themotor speed drops to a proper point.

In order to immediately stop the motor upon the failure of voltage, Iprovide a circuit breaker CB which is so arranged as to apply aneffective dynamic brake to the mo-, tor when the circuit breaker opens.To this end, in the particular form illustrated, I have provided twocontacts 32 and 33 which move into and out of engagement with fixedcontacts asthe circuit breaker closes and opens. The contact 33 engageswith three contacts, two of which close a dynamicbraking circuit throughthe motor and a portion of the brake resistance BR while the other isconnected with the shunt field. The contact 32 engages with twocontacts, one of which is connected with the field terminal while theother is connected with the armature circuit during the dynamic braking.When the circuit breaker is opened the armature circuit is immediatelyclosed through a portion of the resistance BR and the field circuit isclosed across the armature in parallel with the section of brakingresistance.

As thus far described, the arrangement is the same as that disclosed inmy patent application above referred to. I will now de scribe myimprovements whereby the manual control is effected. As before statedthe master controller or reversing switch S is biased to theneutralposition shownin the drawing so that it returns to this neutralposition as soon as the platen of the planer starts to return. The linecontactors for thecutting direction C and-C are energized at the contact10 and the contactors for the return direct-ion R and R" are energizedat the contact 11. In order to hold the contactors closed when thereversing switch returns to this neutral position, I have providedholding circuits which are madethrough the reversing switch in thisneutral position. The holding circuit for the contactors C and C is madeat contact when the contact is raised, the relay will open and insertthe starting resistance l into the motor armature circuita itsupper-position contact 40 makes the manual control circuit throughmanual controlled switches 42 and 43. These switches are shown asnormally open, switches or pushhuttons, those marked 42 being causingoperation in the cutting direction while those marked 43 cause the motorto operate in the return direction The circuit through'the push huttonsi2 is through the interlock 37 on reversing contactor lit, and thecircuit through push huttons is through the interlock 35 on oontactor CCThis makes it necessary that the reversing contactor for one direction.of rotation should he closed. A switch mechanism composed of twoswitches and 45 is provided for changing from automatic to manual control. T have shown this switch mechanism as composed of two switches sothat the change may be made from either of two positionsalthougholbviously this arrangement is not an essential part of myinvention. The arrangement is such that the operation of either one ofthe switches will stop the motor and throw the control from hand toautomatic and vice versa. The operation of either switchmay undo whathas been accomplished by the operation of the other switch. One switchis intended to he on each side of. the planer so that if for instancethe manual control is thrown in by operating a switch on one side of theplaner,

the manual control can be thrown out and the automatic thrownin byoperating the switch on the opposite side of the planer. Or one switchmay be located at the master controller and the other be a pendantswitch convenient to the operator from the upper part of the machine.The return circuit through the line contactors is through the sw'tches44 and 45 both actuating and holdi g circuits returning through theseswitchesto the negative side of the line.

As thus constructed and arranged, the mode of operation of my system isas follows: Assuming switches 4d and 45 in the incense position shown infull lines in the drawing and assuming that the reversing switch orcontroller S has been moved by the dog on the planer into engagementwith contact 10, contactors C and C will he energized from the positiveside or the line through resistance 23, thence through the windings oicontactors C and C in parallel, through the interlock 37 on contactorlit to the contact 10 on the master. controlleigthence through contactto back to the negative side of the line through the switches re and4:5. liesistance 2d is in a parallel circuit with the contactors C and Cand resistance 23 the circuit through this resistance 24 extendingthrough the interlock 26 and back to the negative side of the linethrough wire 4:7. These resistances arevso adjusted that the contactorsC and C will not close until the parallel circuit through the resistance24 is open. The field circuit is made from the positive side or the linethrough the wire.

48, wire 4 through the field winding and the lower winding of? the relay25 wire 15 and switch 16 to the negative side of the line. The relay :25will therefore close hut not until the iield has hecome energized atsubstantially full strength. The closing of the main contacts or therelay 25 has no effect hut the opening of the interlock 25 opens thecircuit of the parallel resistance 24 and causes contactors G and G toclose. line contactors therefore do not close until the field hasreached substantially full strength. Te relay 2'? will also close sinceits lower winding 28 is connected across the line and the winding 29which has a minute"- lelectromotive force coil gradually becomesenergized in a direction to assist winding 28. Contactors C and C aswell as relay '25 and relay 3? are now. closed and the arma- The turecircuit of the motor is therefore closed through the contacts ofcontactors C and C and resistance 5D. The motor willnow start in thecutting direction and as the armature speeds up contactor 12 will closeand short circuit the resistance D of the armature circuit. The closingor this contactor 12 causes a portion of the resistance.

r to be inserted in the field circuit of'the motor, the-field -circuitnow being through the two windings of relay-25, This causes the motor tospeed up due to the insertion tactor B thereupon closes thereby closingthe dynamic brake clrcuit through the motor and the brake resistance BR,causing the contactor 27 to close by reason of thefact of the resistancer in the field circuit and I that the counter electromotive force of thestopping the motor in case it should be run motor is "in a directiontoamist the winding 28 which is across the line. As the field there yshort. circuiting the brake resist .ance BR and bringing the motor torest quickly. Upon the closing of relay 25 the circuit of the resistance24 is opened at the interlock 26 so that the contactors Rand It mayclose. These contactors can only close therefore Whenthe motor isbrought substantially to rest-for. the additional reason that thecontactor'It' cannot close until the brake contactor is opened. Themotor now starts on'its return stroke, the operation being the same asbeforeexcept that the motor is brought up to a higher speed by reason ofthe fact that the resistancer. and a portion of the resistance 4-depending upon the position of the lever 14'will be inserted in thefield circuit. of the motor uponthe closing of relay 12. Likewise whenthe end of the stroke is reached, the operation will be as before but inthis case all of the brake resistance :BR and BR will initially beincluded in the dynamic'brake circuit. This will be the normal mode ofoperation under automatic conditions.

If now it is decided to'operatemanually, thismay be done by throwingeither one of the switches 44 or 45 to' its opposite position. This willhave the effect of immediately ning' and causing the relay 38 tooperate. When the relay 38 closes it completes a hold- .ing' circuit forself, from the positive side of the line through the winding of therelay,

contact 39, segment 41 onthe master controller S and back to thenegativeside of theline. The operation of the relay 38 also denergizes the relay12 and inserts the starting resistance in the armature circuit. Thisisdone by the lifting of contact 40 out of engagement with its lowercontacts. When the contact 40 engages its upper contacts, "a. circuit iscompleted through the push buttons '42 and 43, this circuit being motorfor operatin through wire 50, contacts 40, 39,- and switches '44 and 45.By the operation of one of the switches 44 or 45, the motor has beenstopped. If new one of the push buttons as for instance the cutting pushbutton 42 is pressed, the contactors C and C will be closed, the circuitnow passing from the interlock 37 through the push button 42 and wire 50to the contacts 39 and 40 on the rela 38 in this upper position andthrou'g switches 44 and 45. There is also a circuit from contact 39through the segment 41 on the master switch to the negative side of theline. The motor will therefore start in the cutting direction. Byopening and closing the push button 42', the motor may be stoppedand'started at will. The'motor willing in the wrong direction.

ditions since. both sections of brake resistance are short-circuited- Infact it will stop instantly, this being what is wanted on manualcontrol. When-the end of the stroke is reached, the master switch willbe operthe return circuit of the contactors C and-(Y will still be madeat the switch 44 and 45. Likewise upon pressing one of the push buttons43, the motor may start inthe opposite direction and continue at will.:If now it is" .70 ated but the motor-will'not be-stopped since decidedto return to automatic, one, of the switches 44 or 45 is operated.

tion should start in a return direction, one of the push, buttons 43 ispressed. This Supposing that it is desired that the automaticoperacauses contactors R and R to close and make a maintaining circu'itfor themselves as previously described. The operation will now continueindependently of the push button butat slow speed because the relay 12is open'and resistance D in the motor 'cir--' buit. When the end of thestroke is reached,

the relay 38 will bedenergized at the seg-- ment 41, the relay 12 willclose and the automatic operation will continue in its normal way-With'this arrangement upon chang- I ing toautomatic the operator can fixthe direction which he shall go, without refer ence to the mastercontroller. Furthermore when he closes his circuitbreaker, the motorwill n'ot start until one of the push buttons is pressedso thatthere, isno danger Ofstart will suggest themselves to those skilled in the artwithout departingfrom the spirit.

of my invention. the? scope'of which is set forth in the annexed claims.

What I claima's new and desire to secure by Letters Patent of the UnitedStates, is

1. In combination, a reversible electric planer, manually operatedswitches for controlling the motor for either direction of r0- tationand means independent of the relny. invention as a planer or the like, areversing switch or the motor automatically. operated at the limits oftravel of the' versin switch for changing from manual contro toautomatic control in either direction of rotation as-desired. 2. Incombinatlon, a reversible electrlc motor for operating a planer or thelike, a reversing switch 'for the motor automatically operated .at thelimits of-travel of the planer, manually operated switches for con,-

trolling the motor in either direction of rotation and connectionswhereby the direction in which the motor starts under automatic controlis controlled by the manual switches.

3. In combination, 'a' reversible electric motor for operating a planeror the like a reversing switch for the motor automatically operated atthe limits of travel of the planer, manually operated switches forcontrolling the motor for either direction of rotation, a switch forchanging from manual to automatic control and connections whereby thedirection in which the motor starts when the control is changed toautomatic is controlled by the manual switches.

4. In combination, a reversible electric motor for operatinoa planer orthe like, a reversing switch for the motor automatically operated at thelimits of travel of the planer and biased to an intermediate positionduring the main portion of the travel, manually operated switches forcontrolling the motor for either direction of rotation and a switch incircuit with the reversing switch in its neutral position for changingfrom manual to automatic control.

5. In combination, a reversible electric motor for operati a planer orthe like, a reversing switch l dr the motor automatically operated atthe limits of travel of the planer and biased to an intermediateposition'which it occupies during the main portion of the travel andmanually operated switches for controlling the motor for eitherdirection of rotation and starting the motor in either direction forautomatic control with the reversing switch in its neutral position.

6. In combination, a reversible electric motor for operating aplaner orthe like, a reversing switch for the motor automatically operated at thelimits of travel of the planer and biased to a neutral position which itoccupies during the main portion of the travel, electromagnetic switchesfor controlling the direction of rotation of the motor having actuatingand maintaining circuits made res ective in the operated and neutralposi-- tlons of the reversing switch and manually operated means forcontrolling the motor in elther direction of rotation and starting themotor in either direction for automatic control with the reversingswitch in the-neutralposition.

7. In combination, a reversible electric motor for operating a planer orthe like a reversing'switch for the motor automatically operated at thelimits of travel of the planer and biased to. an intermediate positiondurmg the main portion of the travel, electro:

magnetic switchesfor controlling the direcmotor for operating a planeror the like, a

reversing switch automatically operated at the limits of travel of theplaner magnetic switches for controlling the direction of rotation ofthe motor controlled by the reversin switch and having actuating andmaintaining circuits, manually operated switches for controlling theactuating.

circuits of Said electromagnetic switches, a switch for changing overfrom manual to automatic control and connections whereby a holdingcircuit for said electromagnetic switches is made through the reversingswitch when the said changeover switch is in position for automaticoperation.

9. In combination, a reversible electric motor for operating a planer orthe like, a reversing switch automatically operated at the limits oftravel of the planer and biased to an intermediate position during themain portion of the travel, electromagnetic switches for controlling thedirection of rotation of the motor having actuating circuits made whenthe reversing switch is operated and maintaining circuits made in. theintermediate position of the reversing switch, manually operatedswitches for controlling the 'actuating circuit of the electromagneticswitches a relay controlling the circuit through the manual switches anda change over switch having connections for completing the maintainingcircuit of the electromagnetic switch in one position and energizing therelay in another position.

In witness whereof, I have hereunto set my hand this 22nd day of April,1915.

JOHN EATON.

electro-

